NOTATIO

The "two voices in one staff" puzzle by OCTO reminded me of a similar situation I encountered recently: here, too, the tie placement was problematic. Below you can see the best I could come up with. But I really dislike the tie between the high D flats being so far away from the noteheads.
I'd be curious if anyone could find a different solution?

erelievonen wrote:But I really dislike the slur between the high D flats being so far away from the noteheads.

I think it is not a slur, but a tie.
I find your solution very good, I can't come with something better, you had to make really many compromises.
This is a truly hard example, with a lot of spacing/tie issues!

Thank you, OCTO. And of course, I meant to write "tie", not slur.

That looks like a possible alternative, John. I had in fact also tried to put the D flat tie above, but then it had to cross through all of the three other ties. It didn't occur to me to draw one of the longer ties under (through the stems of the lower voice). There was also another issue, though - in your version as well - which is that the beginning of the D flat tie is quite obscured by being too close to the other slurs. What is the best compromise here is anyone's choice, I guess...

It is interesting that in spite of all the traffic, I don't find the beginning of Db tie to be at all obscured. In fact, it stands out like a sore thumb to me, perhaps because I am reading the entire entity: the whole tie with the two Db's at each end. It is in the first version that I would have trouble relating the tie to the notes themselves because the tie again does not really connect the note heads themselves.

I am not trying to defend my version, just reporting my actual visual reaction, which is, of course, what you are doing as well.

I have a feeling that there would be a lot of this kind of thing in Boulez's piano music but I don't have anything handy.

It is definitely a hard example, and with respect to you John, I find ere's example to be the best possible solution.

I think open ties is a viable option in this case:

I prefer the open tie solution over my own and the OP.

yes, open solution is also very good. I wanted to make this one, but preferred to keep the ties just for exercising.
If the open ties are not problem for Ere, I think that is a very good solution.